1. Field of the Invention
The present invention relates to a battery managing technique employed in an electronic apparatus on which a plurality of types of battery can be simultaneously mounted.
2. Description of the Related Art
Recently, various types of battery-powered portable electronic apparatus, such as portable information terminals called personal digital assistants (PDAs) and digital cameras, have been developed and are widely used.
Further, great attention has been paid to environmental problems, and environment-friendly batteries are now being actively developed. As batteries of this type, direct methanol fuel cells (DMFCs) are well known.
In DMFCs, methanol is used as a fuel that reacts with oxygen to generate electricity. DMFCs have a structure in which two electrodes, formed of porous metal or carbon, are connected via an electrolyte solution (see, for example, “All about Fuel Cells” by Hiroyuki Ikeda, published by Japan Jitsugyo Publishing, Co., Ltd., Aug. 8, 2001, pp 216–217). Since DMFCs do not generate toxic substances, there is a strong demand that they be used in the above-mentioned electronic apparatus.
For example, a personal computer can now use various types of power sources, such as a conventional external AC power supply, a secondary battery (e.g., a lithium (Li) ion battery), and a DMFC.
Since a personal computer can use a DMFC, secondary battery and AC power supply, it is desirable for users to be able to set, by means of a simple operation, which power source to use, and when to use that power source. Further, when setting the source, it is desirable for users to be able to easily confirm the setting and the source currently in use. In other words, there is a strong demand for a user interface that can display the states of setting and use so that users can grasp it at a glance, and that permits users to make various types of setting by a simple operation.
Conventional electronic apparatuses do not provide such a user interface.